Perpetual Motion

Perpetual motion is something which will never be obtained the simple reason being that nothing lasts forever, the parts of every machine will eventually degrade and wear and this will cause the motion to stop. However this does not mean that we cant strive to come close to perpetual motion and it definitely does not mean that some of these machines would not have the potential to produce energy without the use of fossil fuels.

The video above shows an invention which could possibly be as near to perpetual motion as can be obtained. It was invented by Mr. Reidar Finsrud and the steel ball has been rotating for months now.

The picture on the left shows the first recorded attempt at using a perpetual motion machine for useful work i.e. driving a millstone. The idea is that of Robert Fludd's water screw perpetual motion machine from 1616, the picture itself comes from a 1660 woodcut.

Perpetual Motion from Gravity

Energy can be obtained from gravity by letting a weight fall from a height, an example of this would be weights which power an old grandfather clock. The idea of using gravity to power a perpetual motion machine dates back to an Indian Author called Bhaskara in the 12th centaury.

Bhaskara describes a wheel which has a number of tubes filled with mercury connected to it. These tubes are set at specific angles so that on one side of the wheel the mercury pools closer to the centre of the wheel and on the other side the mercury pools away from the centre of the wheel.

Another example of the same principle was that of the French architect and mason Villard de Honnecourt. He described a wheel which consisted of an uneven number of mallets attached to the wheel. He believed that at any time there would be more mallets on one side than the other and so there would be more weight on that side causing the wheel to spin.

Another variation of this design allows the weighted end of the hammer to rest further out on one side of the wheel than the other. Thus increasing the radius of gyration of that weight.

The type of device Bhaskara describes is known as the overbalanced wheel, which has been popular with inventors through the ages. The idea is to create a moment about the axle of the wheel; this is done by making the moment due to gravity on one side of a wheel greater than the moment due to gravity on the other side. The wheel would have equal masses surrounding it and gravity remains constant. Also the force due to gravity can be found from:

Force = (Mass)(Acceleration)

The moment created by each weight can be given by:

Moment = (Force)(Radius)

To make the wheel spin the sum of the moments must not equal zero, the only way to ensure this happens is to change the radius. I've made up an example of the calculations for this here.

Perpetual Motion using Magnets

The ability of magnets to attract and repel each other despite the non exsistence of an apparent source of energy has sparked people's imaginations for centuries.

One such idea is to create a wheel with a number of natural magnets fixed to it at specific angles and place this wheel in a frame with opposing magnets surrounding the wheel. The idea being that the magnets repulsion would cause the wheel to spin forever. Unfortunately the problem here is that the magnets will begin to move but the magnetic field cannot be confined to a linear path as there is no apparent material yet known that will insulate magnetic fields. With this taken into consideration the magnets will move from its initial point where the magnets are beside each other and move to the point of minimum potential energy which would be exactly half way between each magnet. Therefore i must conclude that this idea for perpetual motion will not work.

Another method of the same idea, which has been posted on youtube, does not fix the magnets of the wheel in place. The magnets are rotated as the wheel spins i.e. the magnets attract as they move towards each other while this is happpening the spinning magnet is rotating in such a way so that when it becomes level with the fixed magnet in the frame it is at 90 degree's to it. At this point the opposite end of the rotating magnet takes affect pushing the wheel around and thus the cycle continues. I dont know how to calculate this as the working out how magnets act on each other is beyond my capabilitys at the minute so the best method to test this would be to replicate it.

An idea which dates back to 1600's and the then Bishop ofChester John Wilkins is the idea that a magnet could pull a steel ball up a ramp where it would then fall through a hole to the bottom and follow a path which would lead back to the bottom of the ramp which would result the cycle repeating. The problem with this design is that it would require quite a strong magnet to get the steel ball to climb the ramp in the first place and such a magnet would most likely keep the steel ball at the top of the ramp. It is for this reason I believe this idea flawed and wont work.